Crimp terminals for an aluminum electric cable of this type include a crimp terminal for an aluminum electric cable as shown in FIG. 1 and FIG. 2. The technique is disclosed in FIG. 1 of a Japanese Patent Application Laid-Open No. 2007-173215 (Patent Document 1). As a prior technique other than the just-mentioned technique, there exists a crimp terminal for an aluminum electric cable as shown in FIG. 7 of Japanese Patent Application Laid-Open No. 2003-249284 (Patent Document 2).
As shown in FIG. 1, this crimp terminal 1 for an aluminum electric cable includes: a fastening part 2 in which a through-hole 2a is formed; and a crimping part 3 in an almost U-letter shape. The through-hole 2a allows fastening means (not illustrated) such as a bolt to pass therethrough. The crimping part 3 is connected to a core wire 6 of an aluminum electric cable 5 by crimping. Multiple aluminum strands 6a are twisted together to form the core wire 6. Multiple serrations 4 are formed in an inner surface 3a of this crimping part 3. The serrations 4 extend in a direction orthogonal to a lengthwise direction of the core wire 6.
Once the core wire 6 of the aluminum electric cable 5 is crimped by the crimping part 3 of the crimp terminal 1 for an aluminum electric cable by pressure of squeezing as shown in FIG. 2, an oxide film of a surface of each aluminum strand 6a of the core wire 6 is broken by grooves of the multiple serrations 4, and a fresh surface (aluminum surface) of the aluminum strand 6a is exposed. Thus, the core wire 6 of the aluminum electric cable 5 is electrically connected to the crimping part 3 of the crimp terminal 1 for an aluminum electric cable.
Nevertheless, in a case where a thick (large-diameter) aluminum electric cable 5 having a larger number of aluminum strands 6a is connected to the conventional crimp terminal 1 for an aluminum electric cable, it is difficult to break an oxide film of a surface of an aluminum strand 6a situated in the core (center) of the core wire 6. Under this situation, an electric current can flow only in aluminum strands 6a situated in the outer side of the core wire 6, which facilitates generation of convergence resistance. This resistance causes troubles such as a rise in the temperature of the core wire 6 and failure in electric conduction thereof.
The present invention has been made to solve the problem described above. An object of the present invention is to provide a crimp terminal for an aluminum electric cable which is capable of obtaining better electric connection by securely breaking an oxide film of a surface of a core wire situated in the center portion.